Rubbery diene synthetic elastomer composition



RUBBERY DIENE SYNTIETIC ELASTOMER COWOSITION Larry Jacobson, Painesville, Ohio, assignor to Diamond Alkali Company, Cleveland, Ohio, a corporation of Delaware No Drawing. Application August 2, 1954 Serial No. 447,397

23 Claims. (Cl. 260-285) This invention relates to synthetic elastomer compositions of improved tensile strength and tear resistance, as well as improved processing and loading qualities.

The term synthetic elastomer as used herein is that commonly used in the rubber compounding art to designate those synthetic organic polymers and copolymers having appreciable olefinic unsaturation remaining in the molecules thereof after polymerization, so as to render such polymer and copolymer materials v-ulcanizable under the influence of a vulcanizing agent in conjunction with heat and pressure. These polymers may be further characterized by their ability, in the vulcanized state and in the form of a standard test piece, to be stretched to at least twice the original length of such test piece, and upon removal of the stress after such stretching to return to approximately the original length within a short time.

Such synthetic elastomers are exemplified by polymers of butadiene and copolymers of butadiene and styrene, copolymers of butadiene and acrylonitrile, and copolymers of iso'butylene and butadiene, copolymers of isobutylene and Z-methyl butadiene (isoprene), and copolymers of 2-chlorobutadiene and styrene (chloroprene). The proportions of the various components of the copolymer mixtures and their effect upon the physical properties of the elastomers are well-understood in the art.

This application is a continuation-in-part of my copending application Ser. No. 288,327, filed May 16, 1952, noW abandoned.

It has heretofore been proposed to combine specific chlorinated organic materials in specific amounts with various plastic materials for such purposes as flameproofing the plastic material, for preventing scorching of vulcanizable synthetic elastomers, and for plasticizing various synthetic plastics.

In the flameproofing of plastic materials, the proposals heretofore made for the incorporation of chlorinated organic compounds have been limited to the combination consisting essentially of a given plastic material with a mixture of a chlorinated organic compound plus an inorganic flame-retardant substance, such as salts of antimony, arsenic, and bismuth, as well as oxides of these elements. Obviously, versatility of such compositions is not one of their virtues, and this is requisite particularly in the art of manufacturing mechanical rubber goods which find a wide variety of uses.

The proposed methods to employ a chlorinated organic material, particularly chlorinated paraffin wax, to prevent scorching during the processing of synthetic elastomer compositions containing carbon black, required only very small amounts of the chlorinated parafiin wax to overcome the effects of high pH of the carbon black fillers. Whatever the virtues of such methods may be, it has been found that little other than the prevention of scorch ing is accomplished.

Similarly, in the fiameproofing of synthetic elastomers, the prior proposals have been directed to the use of comparatively small amounts of highly chlorinated paraflin wax together with inorganic flameproofing ingredients.

The loading or amounts of inorganic flameproofing materials, to be used in such compositions, in accordance with these proposals, has been well under of the synthetic elastomers employed; changes in the physical properties, other than flameproofing, resulting from the use of the combination of highly chlorinated parafiin wax with inorganic filler materials, have not shown marked improvement. In fact, in accordance with certain of these proposals, the physical properties of the compositions have generally shown a decrease, in that tensile strength, tear resistance, and hardness, have been impaired, at the expense of acquiring only flame resistance or fiameproofing of the compositions.

The proposed compositions for employing chlorinated organic materials, particularly chlorinated paraflin Wax containing from 35 %55 of chemically combined chlorine, have not been found to be the equivalents, nor to impart the same physical properties to synthetic elastomer vulcanizates, as the compositions of the present invention.

One of the objects of the present invention is to provide synthetic elastomer compositions of greater versatility than the compositions heretofore proposed in the art of compounding and manufacturing such compositions.

Another object of the invention is to provide synthetic elastomer compositions having a greater loading capacity with respect to pigments of the reinforcing type, and fillers commonly employed in this art.

A further object of the invention is to provide synthetic elastomer compositions, particularly those containing the butadiene-styrene copolymers, requiring less milling time to incorporate reinforcing pigments, and fillers, than has heretofore been experienced in the art.

A still further object of the invention is to provide synthetic elastomer compositions in which shrinkage after milling is substantially negligible.

Another object of the invention is to provide synthetic elastomer compositions of improved physical properties containing highly chlorinated parafiin wax and a high proportion of filler materials relative to the amount of synthetic elastomer in the composition.

These and other objects will be apparent from the description of the invention provided hereinbelow.

As a basis for the objects of the invention, it has now been found that chlorinated paratfin wax containing from 65%75% of chemically combined chlorine, when included in synthetic elastomer compositions of the abovedescribed class, and containing inert inorganic fillers or reinforcing pigments, or both, to the extent of 100%, or more, of the elastomer, impart several highly desirable properties to such compositions.

For example, in the processing of synthetic elastomer compositions, particularly those containing butadienestyrene copolymers, and inert inorganic loading materials, such as fillers and reinforcing pigments, to the extent of 100%, or more, of the elastomer, and chlorinated paraffin wax (65%75% of chemically combined chlo rine), the time required to incorporate the loading materials into the mix (the so-called milling time) may be reduced to an interval amount to about one-half of that required to accomplish the same degree of dispersion with the same amount of loading in the synthetic elastomer composition when the chlorinated paraffin wax containing from 65%-75% or" chemically combined chlorine is not present in an amount within the scope of the present invention. Moreover, in mixing stocks for molded mechanical goods, wherein a relatively high degree of loading is either required or desirable, i.e., above about 300% of the elastomer, it has been found that incorporating a proper amount of highly chlorinated parafiin wax, as above specified, not only results in the stock being more easily processed, but also it is possible by the incorporation of the proper amount of such highly Patented July 14, 1959v chlorinated parafiin wax to obtain a much higher loading of the milled stock without impairing substantially either the tensile strength or the tear resistance of the vulcanizate obtained from such stcok. In addition, these stocks, as: well as those. with a lesser degree of loading, are: more. readily. extruded and. calendered than stocks havingthesame degree of loading but lacking the highly chlorinated parathn wax.

Where the degree of loading of the synthetic elastomer stocks is of the order of 100% to 200% of-the elastomer, it has been found that incorporating a proper amount of the. highly chlorinated parathn wax, as above specified, in addition to accelerating the rate at whichthe fillers andreinforcing pigments are dispersed in the stock, also results in the stock adhering less strongly to the processing equipment. The shrinkage of the loaded and unloaded milled stocks is also substantially negligible, i.e., dimensional stability of the uncured stock is assured under normal storage conditions in the interim between milling and the moldingof the stock. Moreover, a vulcanizate is obtained which has higher tensile strength and improved tear resistance, without loss of elasticity, than is obtained from a stock containing the same ingredients in the same amounts without the highly chlorinated parafiin .wax.

Commensurate with these findings, the present invention is directed to synthetic elastomer compositions of improved processing properties, high tensile strength, and improved tear resistance, including a vulcanizable syntheticelastomer, as defined above, a vulcanizing agent for said elastomer, a vulcanization accelerator for said agent, an inert inorganic loading material having an average particle. size substantially within the range. of from 0.02 micron to 15 microns, the Weight ratio of said loading material to said elasto-mer being substantially within the range of 1:1 to 3.5 :1, and chlorinated paraffin wax,

having between 65%75% of chemicallycombined chlorine, the weight ratio of said chlorinated paraffin wax to the said elastomer being substantially withinthe range of 1:20 to 1:1.

In the manufacture of the compositions of the present invention, the general principles of the methods .heretofore employed in the art for obtaining natural and synthetic rubber stocks are followed, For example, the mill or mixer, such as a 2-roll mill or a Banbury mixer, initially is brought to a suitable temperature for softening and masticating the elastomer prior to physicallycombining the dry loading ingredients with the elastomer. For this purpose, a temperature, such as 210 F, plus or minus 5l0, is ordinarily suitable. The elastomer is then masticated for a period sufficient to render the same tacky and. readily fiowable under pressure. The time required to bring the synthetic elastomer to this condition will vary according'to the nature of the polymer or copolymer employed. After the proper degree of breakdown of the elastomer has been obtained, it is common practice to add to the elastomer any plasticizer or plasticizers which may, for one reason or another, be desirable, depending upon the ultimate use to which the vulcanizate obtained from the stock is put. At the same time, any anti-oxidant material which may be desirable in the stock or in the ultimate vulcanizate is added. Thereafter, vulcanization activators, such as zinc oxide, and accelerators which may be derivatives of carbon bisulfide, such as mercaptobenzothiazol, benzothiazol disulfide, tetramethyl thiuram monosulfide, and the like, derivatives of guanidine, such as diphenyl guanidine, di-orthotolyl guanidine, and the like, as well as aldehyde-aromatic amine derivatives, are added. When all of these ingredients have been thoroughly dispersed in the masticated mass, the inert inorganic fillers and reinforcing pigments are added to themass on therolls or in the mixer. dispersion of the fillers and the reinforcing pigments in thebatch, the vulcanization agent, such as elemental sulfur, is added and thoroughly dispersed therein, after-which Following the 4- the batch is removed from the mill'and prepared for molding.

The chlorinated parafiin wax containing from 65 75 of chemically combined chlorine, as specified herein, may be incorporated into the elastomer stock along with the plasticizer and anti-oxidant in the second step of the conventional method described above, or it may be separately mixed with the inorganic. fillers and reinforcing pigments, preferably as a dry comminuted power, and this mixture added to the stock being milled. been found advantageous to combine the solid, preferably comminuted, chlorinated paraffin wax with the tire for the drill extending therethrough toward the fillers and reinforcing pigments. either by passing the mixture of chlorinated paraffin wax and filler or pigment through a hammer mill, or by ball milling the mixture prior to adding the same to the elastomer stock.

Because of the relatively high temperatures and pressuresencountered in the milling operation, as well as in the molding of the milled stock to obtain a vulcanizate from such elastomer compositions, it is preferably to add a stabilizer for the chlorinated paraffin wax to the compositions-of the present invention. This may be accomplished bymixing the. chlorinatediparaifin. wax with a suitable stabilizer and adding this mixture either to the.

elastomer stock during the milling thereof, or to the mixture of filler and reinforcing pigment; also, the stabilizer for the chlorinated paraffin wax may be added to the stock along with the chlorinated paraffin wax, fillers, and pigments without prior mixing. Suitable stabilizers for this purpose include ester salts, such as. alkali 1 metal. organo-phosphates, organo-metallic salts, such as .dibutyl tin -maleate,- heavy metal soaps, such as cadmium and' strontium soaps, barium and cadmium. laurates, barium ricinoleate, and the like, and inorganic compounds, such as dibasic leadphosphite, basic lead silicate-sulfate (double salt type), and the like.

In addition to the above ingredients, it is desirable to incorporate in the elastomer stock a slightly greater amount of accelerator than is normally employed, for the reason'that the chlorinated paraffin wax is characteris-. tically slightly acid and, therefore, tends to retard the rate of vulcanization even in admixture with the normal amount of vulcanization accelerators.-

T'he inert inorganic loading. material, comprisingone or more fillers and reinforcing pigments, used in thecompositions of thepresent invention includes barium. sulfate, calcium carbonate, calcium silicate, calcium sulfate, magnesium carbonate, magnesium silicate, aluminum silicate, the natural complex aluminumsilicates known as clays, silica, magnesiumoxide, zinc -oxide,.zinc sulfide, and like materials. Zinc oxide, in additionto being a filler material, is also a vulcanization activator for the accelerator and vulcunizing agents normally employed in. elastomer. stocks.

Carbon black; aswell ascertain members of the above group, are also regarded as reinforcing, and semi-reinforcing, pigments when the ultirnate particle-size of such materials has been reduced to less than 1 micron. Such materials include the hard clays, the alkaline earth silicates, silica fiour, titanium dioxide, (known-in the rubbercompoundingart as .whitecarbon black), as well as calcium sulfate, and calcium and magnesium carbonates. Theother members of the group of loading materials noted. above may-have particles within and without the range of 0.02-l micron, with a greater proportion of the particles above 1 micron. These materials such as ground limestone (5-l5 microns), the soft clays-having an average particle size above 2 microns, and the like areregarded as--fillers without reinforcing properties.

The amount of loading material to be-incorporated into a given mix may vary from about parts by Weight to about 350-parts by Weight-'per IOO parts by Weight of synthetic elastomen- Maxi-mum utility of the It has also chlorinated paraffin wax is obtained in the more highly loaded formulations where the dispersing effect of the chlorinated parafiin wax upon the loading materials is evidenced by a shorter milling time (of the order of one-half) required to incorporate the loading material into a given mix, uniformity, of the dispersion of loading material in the elastomer as evidenced by the ab sence of aggregates of particles of loading material in the mix, as well as higher tensile strength and improved tear resistance obtained in the vulcanizates, as compared to equal loadings without the chlorinated paraflin wax. This dispersing eifect is, in general, especially notable in formulations having weight ratios of loading material to elastomer above 111, i.e., where the weight of the loading material exceeds the weight of elastomer; the reinforcing effect of certain loading materials, such as carbon black, is augmented in the vulcanizates of the compositions of the present invention at ratios within the ranges given above.

Certain inert inorganic compounds which impart color to the elastomer stocks, such as ferric oxide, antimony sulfide, titanium dioxide, zinc sulfide, and chromium sesquioxide, may also be employed. The amount of these materials to be used in any given mix is necessarily dependent upon the ability of the particular material to impart the desired shade of color to the elastomer stock.

In addition to these materials, organic dyes may also be incorporated in the stock to impart the desired shade or color to the vulcanizate.

In order that those skilled in the art may better understand the present invention and in what manner the compositions thereof may be obtained, the following specific examples are offered:

In the examples, the data for tensile stress, or modulus, and tensile strength are given in pounds per square inch, and the tear resistance is given in pounds per inch of thickness. The test specifications are fully set forth in the American Society for Testing Materials Standard Methods of Testing, designations D412-4l and D624- 44, respectively.

EXAMPLE I A butadiene-styrene copolymer is used as the synthetic elastomer. This material contains 20% of bound styrene, the particles of the synthetic elastomer being coated with a fatty acid material to the extent of about 6% of the copolymer. This material has been disclosed in the art under the designation of GRSX630.

The method of processing the mix is substantially that set forth in the forepart of this specification.

Table 1 Basic formula: Parts by weight GRSX63O 100 ZnO 5 Stearic acid 1 Benzothiazol disulfide 1. 5 Cu-diethyl-dithiocarbamate. 0. Sulfur 2. 6

To batch No (1) (2) (3) (4) Add: Chlorinated paraffin wax (69%7l%0l). 0 10 Cure-20 min. at 307 F.:

Tensile Stress At 200% elongation. 140 110 120 100 At 300% elongatiom 250 310 260 200 Tensile Strength- At break point 260 350 330 320 Percent Elongation at Break 320 320 360 395 Tear Resistance 37 37 33 It will be observed that this is a simple formulation involving a synthetic elastomer, and zinc oxide as a filler and vulcanization activator, with the usual vulcanization accelerators and vulcanizing agent. Also, it will be noted that from this formulation, there is -a definite reinforcing effect to be obtained by the addition to the stock of as little as 10 parts by weight of a chlorinated parafiin wax (comminuted) containing between 69%- 71% of chemically combined chlorine per parts by weight of synthetic elastomer.

EXAMPLE II Following the same procedure as that employed in Example I, the basic formula of Example I is augmented by the addition thereto of calcium carbonate having a particle size sufliciently small to be regarded as a reinforcing pigment, together with a larger size particle size calcium carbonate suitable for use as a filler material. The amount of calcium carbonate is well over the critical amount for the reinforcing pigment used. That is, in the type of formulation given below, increasing the amount of calcium carbonate (reinforcing grade) up to about parts per 100 parts of the copolymer used causes an increase in tensile strength and tear resistance; however, beyond this critical amount the tensile strength decreases until the amount of reinforcing calcium carbonate filler reaches about parts per 100 parts of copolymer, and then shows little further decrease at loadings substantially above this amount. The decrease in tensile strength, however, as is shown in the table below, may not be sufiiciently great to bring the value down to, or below, the value for the unfilled stock.

Table 2 Basic formula: Parts by weight GR-S-XGBO l0 ZnO Stearic acid Benzothiazol disulfide Ou-diethyl-dithiocarbamate. Sulfur To batch No (5) (6) (7) It will be noted from the above formula that first of all, the addition of a reinforcing pigment to the basic formula of Example I adds considerably to the tensile strength and tear resistance of such composition. In addition, it will be noted, when comparing the tensile strength at the break point for the various compositions, as well as the tear resistance thereof, that there is a striking increase in the tensile strength at the break point for those compositions containing as little as 5 parts of chlorinated paraflin wax (69 %-71% of chemically combined chlorine), and that the tensile strength at the break point further increases as the amount of chlorinated parafiin wax increases in proportion to the amount of synthetic elastomer in the stock. The data for tear resistance in the above table also bring out strikingly the increase in the tear resistance of the cured compositions as the amount of chlorinated paraffin wax is increased in proportion to the amount of synthetic elastomer in the stock, while the amounts of the reinforcing pigment and the filler material are kept constant.

EXAMPLE 1H Methods of -1 compounding these compositions are substantially the same as those employed in the previous examples.

Table 3 Basic formula: Parts by Weight GR-S-XGBO 100 ZnO 5 Stearic acid 1 1 Benzothiazol disulfide 1. 5 Cu-diethyl-dithioearbamate 0. Sulfur" 2. 5

To batch No (9) (l0) (l1) (12) Add:

02005 (0.05-0.06 mu) 200 250 200 250 09.003 (l mu) 50 50 50 50 Chlorinated paraflin wax (69%7l% Cl) 20 Cumarone-indene (resinous copolymer) 20 20 Cure-20 min. at 307 F.:

Tensile Stress- At 200% elongation. 520 760 At 300% elongation. 400 070 660 870 Tensile Strength At break point 1,020 880 920 870 Percent Elongation at 510 385 455 300 Tear Resistance 142 155 157 181 It will be noted from the above table that when the loading of the composition is increased to an amount ranging from 250300 parts of the reinforcing pigment and the filler per 100 parts of synthetic elastomer, both with the cumarone-indene copolymer and with the chlorinated paraffin Wax, a substantial increase in the tensile strength of the cured composition is obtained, over the compositions Without either chlorinated parafiin wax or cumarone-indene copolymer. the break point for all four of these compositions is of the same order of magnitude, but with a substantial increase in the tear resistance of the composition containing the highest loading and 20 parts of chlorinated paraffin wax (69%7l% Cl) per 100 parts of the synthetic elastomer. In addition, and a fact which is not noted in the table, there is a substantial decrease in the milling time of the compositions containing the chlorinated paraffin wax; specifically, the milling time is reduced by about one-half of the milling time required for the composition containing the cumarone-indene copolymer.

EXAMPLE IV The synthetic elastomer employed is GR-S 100, a butadiene-styrene copolymer well-known in the art of rubber compounding. This material is a low temperature polymerizate containing about 6% rosin acid. The formulae in the tables below show the effect of adding chlorinated parafiin wax (69%71% C1) to a simple formulation such as that shown in Example I above, and to a filled formulation such as that shown in Example 11 above. In the filled formulations, it is to be noted particularly that the filling agent is of a relatively coarse texture when compared with so-called reinforcing agents, and that the amount of the loading material used is well past the critical amount as noted by comparing the tensile strength values of the filled and unfilled compositions.

Table 4 Basic formula: Parts by weight GR-S 100 100 ZnO 5 Stearie acid l Benzothiazol disulfide. 1.5 Tetramethyl thiuram disul 0. Sulfur 2. 5

To batch No (13) (14) (15) (16) Add: Chlorinated paraflin wax (69%-7l% Cl 10 20 Cure20 min. at 307 F;

Tensile Stress- At 200% elongation 120 120 100 80 At 300% elongation 190 200 150 130 Tensile Strength- At break point 220 260 250 300 Percent Elongation at Bre 330 350 420 485 Tear Resistance 28 32 29 34 The tensile strength at Table 5 Parts by Basic formula: weight GR-S 0 ZnO 5 Stearie i 1 Benzothiazol disulfide 1. 5 Tetramethyl thiuram disulfide. 0.25 CaCOa (approx. 5 mu.) Sulfur 2.

To batch No (17) (18) (19) (20) Add: Chlorinated paraffin wax (69%71% Cl) 10 20 30 Cure-30 min. at 307 F.:

Tensile Stress- At 200% elongation 140 130 At 400% elongation 230 260 250 260 Tensile Strength At Break point 230 270 310 330 Percent Elongation at Bree 400 420 460 500 Tear Resistance 37 48 45 52 A comparison of Tables 4 and 5 points up the unusual eifect to be obtained by the addition of chlorinated paraffin wax to a physical combination of elastomer and inert inorganic filler material of relatively large particle size. Thus, it Will be observed that batch Nos. (13) and (17) show substantially no diiferences as to tensile strength of vulcanizate at the break point, whereas this value increases markedly in the range of lO-30 parts of the chlorinated parafiin Wax per 100 parts of elastomer, all with the same amount of non-reinforcing filler material. Moreover, there is a corresponding increase in the elaasticity and tear resistance of the vulcanizates well above the values of the control batch Nos. (13) and (17).

EXAMPLE V The formula given in the table below will be recognized as a slight variation of that given in Example III, using GR-S 100, and physical test data show the efiect, upon the tensile strength and the tear resistance, of employing as little as 5 parts of chlorinated paraffin wax per 100 parts of the synthetic elastomer and employing substantially less loading material than that of Example III, although the amount of loading material is still well over the critical amount for the copolymer and calcium carbonate used.

Table 6 v Parts by Basic formula: weight GR-S 100 100 5 1.5

Ou-diethyl-dithioearbamate s 0 25 Oil soluble sulfonic acid-l-paratfin oil...

With this amount of loading, it will be observed that the chlorinated paraffin Wax material very definitely exerts a reinforcing effect upon the mixture of inorganic loading material and synthetic elastomer, equivalent at least to that of the cumarone-indene copolymer, and

EXAMPLE VI There is employed a butadiene-acrylonitrile copolymer designated by the manufacturer (The B. F. Goodrich Company) as Hycar, with further designation to indicate oil resistance and easy processing. Also, a semi-reinforcing furnace black, and a high modulus furnace blac are employed as the filler materials, and it Will be noted that a large proportion of chlorinated paraffin wax (69%7l% of chemically combined chlorine) is employed relative to the amount of the synthetic elastomer material.

The antimony oxide noted in the tables below is present for the purpose of imparting flame-retarding properties to the mix, since these formulae are representative of flame-resistant wire coating compositions.

Table 7 Parts by weight Basic formula:

Hycar or 25 EP ZnO Mercaptobenzothiazol Stearic acid To batch No It will be noted that the critical amount of loading for the semi-reinforcing furnace black is about 100 parts per 100 parts of copolymer, and that the relatively high proportion of chlorinated parafiin wax causes an unusual increase in the tensile strength value at the critical amount of loading material, thus, again emphasizing the substantial reinforcing effect obtained from the chlorinated paraflin wax. When the critical amount of loading is lower, as with the high modulus furnace black, and this critical amount is considerably exceeded, as in batches 28 and 29, the reinforcing effect of chlorinated paraflin wax is still very much in evidence.

EXAMPLE VII The physical test data obtained from elastomer compositions containing neoprene W (a general purpose polymer of 2-chlorobutadiene) given in the table below show the plasticizing effect of chlorinated parafiin Wax having less than 65% of chemically combined chlorine, in contrast with the reinforcing effect of chlorinated paraflin wax having more than 65% of chemically combined chlorine.

To batch N0 (30) (31) (32) (33) Add: Chlorinated paraflin wax (50%-62% Cl 30 50 69 Cl 30 50 Cure-30 min. at 307 F.:

Tensile Stress- At 200% elongation 1, 030 660 1, 550 1, 380 At 300% elongation 1, 200 970 Tensile Strength- At break point; 1, 220 1,150 1,630 1, 620 Percent Elongation at Brea 310 455 240 290 Tear Resistance.--" 254 247 276 285 Shore A Hardness 82 72 85 82 It will be noted from the physical data of the above table that While the tensile strength of the three com positions at the break point is substantially the same, the formulae containing the chlorinated paraffin wax are shown to be appreciably more elastic than the material obtained by the representative formula.

EXAMPLE VIII The formula for this example is representative of a table-top backing. The amount of chlorinated paraffin wax incorporated in this formula is increased up to a maximum of 40 parts of the chlorinated paraflin Wax per 100 parts of rubber (synthetic elastomer whole tire reclaim containing 50% rubber hydrocarbon). Also, it will be noted from the data in this table that there is an increase in the tensile strength at the break point, as Well as an increase in the tear resistance, when suitable amounts of the chlorinated paraflin wax are incorporated in the formula, with the degree of loading considerably over the critical amount.

Table 9 Basia formula: Parts by Weight 0 Whole tire reclaim (50% rubber hydrocarbon) Limestone (avg. 10 microns) 60 Mineral rubber 2t ZnO 3 Beuzothiazol d fi 1. 25 Tctramethyl thiuram monosulfide 0.5 Stearic ac 2 Light process oil 1 Sulfur 3. 5

To batch N o (34) (35) (36) (37) l (38) Add:

Dixie Clay 60 70 75 75 75 Furnace black (semire1nf0rcing) Chlorinatedpara (69%71% Cl) 1- 20 30 4O 40 40 Cure-20 min. at 287 F.:

Tensile Stress- At 100% elongation" 640 700 700 870 1, 000 At 200% elongation" l, 030 1, 030 1, 050 1, 270 Tensile Strength- At break point 1, 120 1,150 1, 160 l, 270 1, 270 Percent Elongation at Break 240 230 250 200 Tear Resistance 153 148 177 171 178 EXAMPLE IX In the following table the reclpes and the physical test data illustrate the use of two elastomers in compositions within the scope of the present invention, and certain of the physical properties of such composition. The recipes are for compositions containing butadiene-styrene, and butadiene acrylonitrile, copolymers in combination with neoprene, and having better low temperature flexibility than would be obtained by the use of either of the above copolymers alone. Notable also is the low durometic hardness, coupled with comparatively high tensile strength and flame resistance.

The elastomers used are neoprene WR (a stabilized polymer of 2-chlorobutadiene), GRS 1502 (a butadiene-styrene, low temperature, copolymer, containing an antioxidant), and a butadiene acrylonitrile copolymer designated by the manufacturer (The B. F.

Goodrich Company) as Hycar with a further designation to indicate oil resistance and easy processing.

Table Parts by Weight Batch N o (39) (40) Neoprene WR'I GR-S 1502 Calcium Stearate Physical' Properties (40) Oure-30 min. at 307 F.

Tensile Stress: At 300% elongation Tensile Strength: At break point... Percent Elongation at Break Tear Resistance Hardness EXAMPLE X In the following table there is given a recipe for a mixture containing a high temperature copolymer of butadiene and styrene (GR-S 1001), and a general purpose Z-chlorooutadiene polymer, designated neoprene W. The composition is representative of a gray flameproof deck covering for ships, in which composition'part of the flarneproof properties are derived from the 2- chlorobutadiene polymer.

Table 11 GRS 1001 Parts by weight" Neoprene W Chlorinated paraffin wax /0 1% C1) Antimony 0xide m Zinc oxide Light calcined magnesia Diphcnylguanidine Tetrametnyl thiuram disulfide Benzothiazole disulfidc r s-di-(b-na phthylarnine-pphenylenediamine) do 75 Cd-Ba oleate.- do-.. 85 Stearic acid. 50 Titanium (lion d0 00 Furnace black (to gray colorat do Triethanola'inine do .2 00 Calcium carbonate (1 micron)- -d0 100.00 Suprex clay (1 micron) -do 100.00 fur do 2.00 Physical properties: Oure20 min. at 307 F.-

Tensile stress:

At 200% elongation 820 60 At 300% elongatiom 1050 At 400% elongation 1230 Tensile strength: At bre 1230 Elongation at break 400 Tear resistance 210 Hardness 80 What is claimed is:

'1. A synthetic elastomer composition of improved processing qualities, high tensile strength and improved tear resistance, including a vulcanizable rubbery diene synthetic elastomer material, a vulcanizing agent for said elastomer, a vulcanization accelerator for said agent, an inert inorganic loading material having an average particle size substantially within the range of from 0.02 micron to 15 microns, the weight ratio of said loading material to said elastomer material being substantially within the range of from 1:1 to 3.5: 1, and a solid chlorinated paraffin wax having between 69% and 71%, inclusive, of chemically combined chlorine, the Weight ratio of said chlorinated parafiin wax to said elastomer portion being substantially Within the range of 1:20 to 1:1.

2. The composition of claim 1 in which the vulcanizable synthetic elastomer material is a copolymer of butadiene and styrene.

3. The composition of claim 1 in which the vulcanizable synthetic elastomer material is a copolymer of butadicne and acrylonitrile.

4. The composition of claim 1 in which the vulcanizable synthetic elastomer material is a copolymer of butadiene and isobutylene.

5. The composition of claim 1 in Which the vulcanizable synthetic elastomer material is a polymer of butadiene.

6. The composition of claim 1 in which the synthetic elastomer material is a mixture of synthetic elastomers.

7. A synthetic elastomer composition of improved processing qualities, high tensile strength and improved tear resistance, including a vulcanizable rubbery diene synthetic elastomer material, a vulcanizing agent for said elastomer, a vulcanization accelerator for said agent, an inert inorganic loading material having an average particle size substantially within the range of from 0.02 to 1 micron, the weight ratio of said loading material to said elastomer material being substantially within the range of 1:1 to 3.521, and a solid chlorinated parafiin wax having between 69% and 71%, inclusive, of chemically combined chlorine, the weight ratio of said chlorinated paraffin wax to said elastomer being substantially Within the range of from 1:20 to 1:1.

8. The composition of claim 7 in which the vulcanizable synthetic elastomer material is a copolymer of butadiene and styrene.

9. The composition of claim 7 in which the vulcanizable synthetic elastomer material is a copolymer of butadiene and acrylonitrile.

10.,The composition of claim 7 in which the vulcaniz able synthetic elastomer material is a copolymer of butadiene and isobutylene.

11.-The composition of claim 7 in which the vulcanizable synthetic elastomer material is a polymervof butadiene.

12. The composition of claim 7 in which the synthetic elastomer material is a mixture of synthetic elastomers.

13. A synthetic elastomer composition of improved processing qualities, high tensile strength, and improved tear resistance, including a vulcanizable rubbery diene synthetic elastomer material, a vulcanizing agent for'said elastomer, a vulcanization accelerator for said agent, an inert inorganic loading material having an average particle size substantially within the range of 2-15 microns, the weightratio of said loading material to said elastomer material being substantially within the range of 1:1 to 3.5: l, and a solid chlorinated parafiin wax having between 69% and 71%, inclusive, of chemically combined chlorine, the weight ratio of said chlorinated paraffin wax to said elastomer material being substantially within the range of 1:20 to 1:1.

14. The composition of claim 13 in which the vulcanizable synthetic elastomer material is a copolymer of butadiene and styrene.

15. The composition of claim 13 in which the vulcaniz- 13 able synthetic elastomer material is a copolymer of butadiene and acrylonitrile.

16. The composition of claim 13 in which the vulcanizable synthetic elastomer material is a copolymer of butadiene and isobutylene.

17. The composition of claim 13 in which the vulcanizable synthetic elastomer material is a polymer of butadiene.

18. The composition of claim 13 in which the synthetic elastomer material is a mixture of synthetic elastomers.

19. A synthetic elastomer composition of improved processing qualities, high tensile strength and improved tear resistance, including a vulcanizable synthetic elastomeric copolymer material of butadiene and styrene, a vulcanizing agent for said copolymer, a vulcanization accelerator for said agent, calcium carbonate having a particle size substantially within the range of from 0.02 micron to 1 micron, the weight ratio of said calcium carbonate to said copolymer being substantially within the range of 1:1 to 3:1, and a solid chlorinated paraffin wax having 69% and 71%, inclusive of chemically combined chlorine, the weight ratio of said chlorinated paraflin wax to said copolymer being substantially within the range of 1:201:3.

20. A synthetic elastomer composition of improved processing qualities, high tensile strength and improved tear resistance, including a vulcanizable synthetic elastomeric copolymer of butadiene and acrylonitrile, a vulcanizing agent for said copolymer, a vulcanization accelerator for said agent, carbon black having a particle size substantially within the range of 0.02 micron to 1 micron, the weight ratio of said carbon black to said copolymer being substantially within the range of 1:1 to 1.25:1, and a solid chlorinated paratfin wax having 69% to 71%, inclusive, of chemically combined chlorine, the weight ratio of said chlorinated parafiin wax to said elastomer being substantially 0.85: 1.

21. A synthetic elastomer composition of improved processing qualities, high tensile strength and improved tear resistance, including a vulcanizable synthetic elastomeric polymer of 2-chlorobutadiene, a vulcanizing agent for said polymer, a vulcanization acceleration for said agent, an inorganic loading material including a mixture of carbon black and calcium carbonate having a particle size of the order of 1 micron, the weight ratio of said mixture to said polymer being substantially 23:1, and a solid chlorinated paraflin wax having 69% to 71%, inclusive, of chemically combined chlorine, the weight ratio of said chlorinated paraflin Wax to said elastomer being substantially within the range of 0.3-0.5 :1.

22. A synthetic elastomer composition of improved processing qualities, high tensile strength, and improved tear resistance, including a mixture of a synthetic elastomeric copolymer of butadiene and styrene with whole time reclaimed rubber, a vulcanizing agent for said copolymer and said reclaimed rubber, a vulcanization accelerator for said agent, an inorganic loading material consisting essentially of a mixture of clay, calcium carbonate, and carbon black, said loading material having a particle size within the range of 1-15 microns, the weight ratio of said loading material to the combined weight of said elastomer and rubber hydrocarbon of said reclaimed rubber being substantially within the range of 2.25-2.6z1, and a solid chlorinated paraffin wax containing 69% to 71%, inclusive, of chemically combined chlorine, the weight ratio of said chlorinated parafiin wax to the combined weights of said elastomer and said rubber hydrocarbon being substantially within the range of 0.3-0.4:1.

23. A synthetic elastomer composition of improved processing qualities, high tensile strength, and improved tear resistance, including mixtures of synthetic elastomeric material selected from the group consisting of polymers of 2-chlorobutadiene, copolymers of butadiene and styrene, and copolymers of butadiene and acrylonitrile, a vulcanization agent for said elastomeric material, a vulcanization accelerator for said agent, inorganic loading materials selected from the group consisting of clay, silica, calcium carbonate, and antimony oxide, the weight ratio of said loading materials to said elastomeric material being substantially within the range of 1.35 2.5 :1, and a solid chlorinated paraflin wax containing 69% to 71%, inclusive, of chemically combined chlorine, the weight ratio of chlorinated paraflin wax to said elastomer material being substantially within the range of 0.7-0.85z1.

References Cited in the file of this patent UNITED STATES PATENTS 2,138,192 Ott Nov. 29, 1938 2,480,298 Happoldt Aug. 30, 1949 2,545,977 Smith Mar. 20, 1951 2,590,211 Rugar Mar. 25, 1952 2,669,521 Bierly Feb. 16, 1954 2,727,874 Peterson et al. Dec. 20, 1955 

1. A SYNTHETIC ELASTOMER COMPOSISTION OF IMPROVED PROCESSING QUALITIES, HIGH TENSILE STRENGTH AND IMPROVED TEAR RESISTANCE, INCLUDING A VULCANIZABLE RUBBERY DIENE SYNETHIC ELASTOMER MATERIAL, A VULCANIZING AGENT FOR SAID ELASTOMER, A VULCANIZATION ACCELERATOR FOR SAID AGENT, AN INERT INORGANIC LOADING MATERIAL HAVING AN AVERAGE PARTICLE SIZE SUBSTANITIALLY WITHIN THE RANGE OF FROM 0.02 MICRON TO 15 MICRONS, THE WEIGHT RATIO OF SAID LOADING MATERIAL TO SAID ELASTOMER MATERIAL BEING SUBSTANTIALLY WITHIN THE RANGE OF FROM 1:1 T 3.5:1, AND A SOLID CHLORIANTED PARAFFIN WAX HAVING BETWEEN 69% AND 71%, INCLUSIVE, OF CHEMICALLY COMBINED CHLORINE, THE WEIGHT RATIO OF SAID CHLORINATED PARAFINN WAX TO SAID ELASTOMER PORTION BEING SUBSTANTIALLY WITHING THE RANGE OF 1:20 TO 1:1 